Preheat oven to 375 degrees F (190 C) and line a standard muffin tin with 12 paper liners (as original recipe is written // adjust if altering batch size).
Add graham crackers to a food processor and process until you achieve a fine meal. Then add melted butter and pulse to combine.
Distribute evenly among muffin tins and press down with a glass or spoon to flatten. Bake for 10 minutes or until golden brown. Remove and set aside to cool.
Add all filling ingredients to a blender and blend on high (or liquefy) until creamy and smooth. Taste and adjust flavor as needed, adding more lime zest/juice for more tart, or more agave for added sweetness.
Pour filling into muffin tins and tap on counter to release air bubbles. Top with a bit more lime zest and loosely cover.
Freeze for 2-4 hours or until firm. Remove from the freezer for 10-15 minutes to thaw before serving. Will keep covered in the freezer for up to 2 weeks, though best when fresh.
*You can sub 6-7 key limes in place of 3-4 large limes. *Loosely adapted from Martha Stewart *To keep this recipe gluten-free/grain-free, simply sub gluten-free cookies in place of the graham crackers OR use a walnut-date crust. *Prep/cook time doesn't include freezing. *Nutrition information is a rough estimate.